[36.05] Acceleration of Coronal Mass Ejections in the Low Corona and Association with Surface Activity

W.M. Neupert (NOAA/SEC)

Knowledge of the acceleration of coronal mass ejections
(CMEs) in the low corona is vital in properly relating such
eruptions to prior activity in the chromosphere and low
corona and thereby identifying the processes that initiate
these events. Observations made by the EUV Imaging Telescope
(EIT) on the Solar Heliospheric Observatory (SOHO) have been
used to track off-limb transients, both coronal plasmas and
erupting filaments, from their pre-event locations, through
their periods of maximum acceleration, and into the fields
of view of the white light coronagraphs (LASCO), also on
board SOHO. In all instances studied (limited by the cadence
of EIT observations), CME acceleration as observed in the
EIT images was preceded by filament activity and in one
instance, of an erupting quiescent filament observed against
the solar disk, by the appearance of a new magnetic region
to one side of the filament. This filament activity was
followed by an initially slow increase in height of one or
more faint coronal loops (observable only above the solar
limb) that then accelerated at rates as high as 0.5 km/s/s
between 100 Mm and 750 Mm above the solar surface. For CMEs
that originated on the visible side of the Sun, this
acceleration coincided with a rapid rise in the soft X-ray
flux as measured by GOES. No transient coronal changes that
might suggest reconnection in the higher corona were
observed in the LASCO coronagraph fields of view. These
results imply that the CME is initiated by localized
magnetic activity in the chromosphere or at the very base of
the corona. This work was supported by NASA Contract
NAS5-00220 with L-3Comm/Analytics.